Gaetano Mendola <[EMAIL PROTECTED]> writes: > NikhilS wrote: >> I have tried some update-subselect variations and they seem to work. For >> example the case in the src/test/regress/sql/update.sql, which used to >> fail till now, seems to work: >> >> UPDATE update_test SET (a,b) = (select a,b FROM update_test where c = >> 'foo') >> WHERE a = 10;

> What's the expected result if the tuple from subselect is more than 1? Error, per SQL99 section 7.14: 1) If the cardinality of a <row subquery> is greater than 1 (one), then an exception condition is raised: cardinality violation. > I expect no update at all in case of void result set, is this the case ? No, you get nulls; it's a subquery not a join. Per SQL99 7.1: c) If the <row value constructor> is a <row subquery>, then: i) Let R be the result of the <row subquery> and let D be the degree of R. ii) If the cardinality of R is 0 (zero), then the result of the <row value constructor> is D null values. iii) If the cardinality of R is 1 (one), then the result of the <row value constructor> is R. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly